INTRODUCTION. 



Of Thermotics and Atmology. 



I EMPLOY the term Thermotics, to include all the 

 doctrines respecting Heat, which have hitherto 

 been established on proper scientific grounds. Our 

 survey of the history of this branch of science must 

 be more rapid and less detailed than it has been 

 in those subjects of which we have hitherto treated: 

 for our knowledge is, in this case, more vague and 

 uncertain than in the others, and has made less 

 progress towards a general and certain theory. 

 Still, the narrative is too important and too instruc- 

 tive to be passed over. 



The distinction of Formal Thermotics and Phy- 

 sical Thermotics, of the discovery of the mere 

 Laws of Phenomena, and the discovery of their 

 Causes, is applicable here, as in other departments 

 of our knowledge. But we cannot exhibit, in any 

 prominent manner, the latter division of the science 

 now before us ; since no general theory of heat has 

 yet been propounded, which affords the means 

 of calculating the circumstances of the phenomena 

 of conduction, radiation, expansion, and change of 

 solid, liquid, and gaseous form. Still, on each of 

 these subjects there have been proposed, and ex- 



